Narrow-Band-Imaging-Derived Mean Optical Intensity: A Potential Biomarker for Monitoring the Progression of Oral Squamous Cell Carcinoma

Background/Objectives: This study aimed to explore the potential value of narrow-band-imaging (NBI)-derived mean optical intensity (MOI) in monitoring the progression of oral squamous cell carcinoma (OSCC), from the normal oral mucosa through epithelial dysplasia to invasive carcinoma. We compared differences in the NBI MOI among distinct pathological stages, so as to provide preliminary evidence for its clinical application in auxiliary diagnosis and progression assessment for OSCC. Methods: A total of 40 human oral mucosal specimens (15 normal, 15 oral leukoplakia, 10 OSCC) were enrolled for NBI image acquisition and MOI measurements. A 4-nitroquinoline-1-oxide (4NQO)-induced mouse OSCC model (n = 34) was used to dynamically record MOI changes across different pathological stages. A syngeneic tongue tumor mouse model (n = 16) was further established to evaluate whether MOI could reflect tumor formation and growth. All MOI values were quantified using ImageJ software with standardized region-of-interest (ROI) selection and background correction. Results: In clinical samples, MOI values decreased progressively from the normal mucosa (129.6 ± 5.991 arbitrary units (a.u.)) to oral leukoplakia (OLK) subgroups, including mild dysplasia (104.6 ± 3.757 a.u.) and moderate-to-severe dysplasia (91.77 ± 4.345 a.u.), and further to OSCC (54.41 ± 14.40 a.u.). In the 4NQO model, the MOI of the lingual mucosa was highest in the healthy control group (167.3 ± 10.05 a.u.) and gradually declined with increasing dysplasia severity, reaching the lowest level at the OSCC stage (48.67 ± 10.07 a.u.). In the syngeneic tumor model, the MOI was significantly lower in tumor-bearing mice than in healthy controls (47.85 ± 10.44 a.u. vs. 119.7 ± 14.20 a.u., p < 0.001). Receiver operating characteristic (ROC) analysis demonstrated good diagnostic performance of the MOI in distinguishing healthy tissue from cancerous lesions. Conclusions: NBI-derived MOI may quantitatively reflect the dynamic alterations of the oral mucosa during oral carcinogenesis and could represent a potential biomarker enabling the non-invasive, repeatable early evaluation and dynamic monitoring of OSCC.